共查询到20条相似文献,搜索用时 15 毫秒
1.
L. Romaka Yu. StadnykV.V. Romaka P. DemchenkoM. Stadnyshyn M. Konyk 《Journal of Alloys and Compounds》2011,509(36):8862-8869
The phase equilibria in the Gd-V-Sn and Er-V-Sn ternary systems were studied at 870 K by means of X-ray and metallographic analyses in the whole concentration range. Both Gd-V-Sn and Er-V-Sn systems are characterized by formation of one ternary compound at investigated temperature, with stoichiometry RV6Sn6 (SmMn6Sn6-type, space group P6/mmm, a = 0.55322(3) nm, c = 0.91949(7) nm for Gd, a = 0.55191(2) nm, c = 0.91869(8) nm for Er). Solubility of the third component in the binary compounds was not observed. Compounds with the SmMn6Sn6-type were also found with Dy, Ho, Tm, and Lu, while YV6Sn6 compound crystallizes in HfFe6Ge6 structure type. All investigated compounds are the first ternary stannides with rare earth elements and vanadium. 相似文献
2.
Cheng-Liang Huang Yu-Hua ChienChen-Yi Tai Chi-Yuen Huang 《Journal of Alloys and Compounds》2011,509(9):L150
The microwave dielectric properties and the microstructures of (Mg1−xZnx)Al2O4 (x = 0-0.1) ceramic system prepared by the conventional solid-state route were investigated. The forming of spinel-structured (Mg1−xZnx)Al2O4 (x = 0-0.1) solid solutions was confirmed by the XRD patterns and the measured lattice parameters, which linearly varied from a = b = c = 8.0815 Å for MgAl2O4 to a = b = c= 8.0828 Å for (Mg0.9Zn0.1)Al2O4. By increasing x, the Q × f of (Mg1−xZnx)Al2O4 can be tremendously boosted from 82,000 GHz at x = 0 to a maximum of 156,000 GHz at x = 0.05. The Zn substitution was effective in reducing the dielectric loss without detrimental effects on the ?r and τf values of the ceramics. 相似文献
3.
Rachid Essehli Brahim El BaliSaid Benmokhtar Khalid BouzianeBouchaib Manoun Mouner Ahmed AbdalslamHelmut Ehrenberg 《Journal of Alloys and Compounds》2011,509(4):1163-1171
Crystal structures from two new phosphates Na4NiFe(PO4)3 (I) and Na2Ni2Fe(PO4)3 (II) have been determined by single crystal X-ray diffraction analysis. Compound (I) crystallizes in a rhombohedral system (S. G: R-3c, Z = 6, a = 8.7350(9) Å, c = 21.643(4) Å, R1 = 0.041, wR2=0.120). Compound (II) crystallizes in a monoclinic system (S. G: C2/c, Z = 4, a = 11.729(7) Å, b = 12.433(5) Å, c = 6.431(2) Å, β = 113.66(4)°, R1 = 0.043, wR2=0.111). The three-dimensional structure of (I) is closely related to the Nasicon structural type, consisting of corner sharing [(Ni/Fe)O6] octahedra and [PO4] tetrahedra forming [NiFe(PO4)3]4+ units which align in chains along the c-axis. The Na+ cations fill up trigonal antiprismatic sites within these chains. The crystal structure of (II) belongs to the alluaudite type. Its open framework results from [Ni2O10] units of edge-sharing [NiO6] octahedra, which alternate with [FeO6] octahedra that form infinite chains. Coordination of these chains yields two distinct tunnels in which site Na+.The magnetization data of compound (I) reveal antiferromagnetic (AFM) interactions by the onset of deviations from a Curie-Weiss behaviour at low temperature as confirmed by Mössbauer measurements performed at 4.2 K. The corresponding temperature dependence of the reciprocal susceptibility χ−1 follows a typical Curie-Weiss behaviour for T > 105 K. A canted AFM state is proposed for compound (II) below 46 K with a field-induced magnetic transition at H ≈ 19 kOe, revealed in the hysteresis loop measured at 5 K. This transition is most probably associated with a spin-flop transition. 相似文献
4.
J. Olejní?ek L.E. FlanneryS.A. Darveau C.L. ExstromŠ. Kment N.J. IannoR.J. Soukup 《Journal of Alloys and Compounds》2011,509(41):10020-10024
CuIn1−xAlxS2 thin films (x = 0, 0.09, 0.27, 0.46, 0.64, 0.82 and 1) with thicknesses of approximately 1 μm were formed by the sulfurization of DC sputtered Cu-In-Al precursors. All samples were sulfurized in a graphite container for 90 min at 650 °C in a 150 kPa Ar + S atmosphere. Final films were studied via X-ray diffraction (XRD), scanning electron microscopy (SEM) and micro-Raman spectroscopy. It was found that all samples were polycrystalline in nature and their lattice parameters varied slightly nonlinearly from {a = 5.49 Å, c = 11.02 Å} for CuInS2 to {a = 5.30 Å, c = 10.36 Å} for CuAlS2. No unwanted phases such as Cu2−xS or others were observed. Raman were recorded at a room temperature and the most intensive and dominant A1 phonon frequency varied nonlinearly from 294 cm−1 (CuInS2) to 314 cm−1 (CuAlS2). 相似文献
5.
Jian-Ping Zou Sheng-Lian LuoXing-Hua Tang Ming-Jun LiAi-Qin Zhang Qiang Peng Guo-Cong Guo 《Journal of Alloys and Compounds》2011,509(2):221-225
A new framework compound, [Hg4As2](InBr3.5As0.5) (1), has been prepared by the solid-state reaction of Hg2Br2 with elemental In and As at 450 °C. Compound 1 crystallizes in the space group P63/mmc of the Hexagonal system with two formula units in a cell: a = b = 7.7408(6) Å, c = 12.5350(19) Å, V = 650.47(12) Å3. The crystal structure of 1 features a novel 3D framework, [Hg4As2]2+ with tridymite topology. The optical properties were investigated in terms of the diffuse reflectance and infrared spectra. The electronic band structure along with density of states (DOS) calculated by DFT method indicates that the present compound is semiconductor, and the optical absorption is mainly originated from the charge transitions from Br-4p and As-4p states to Hg-6s and In-5p states. 相似文献
6.
Hongyi Li Shilie Pan Hongping WuJared P. Smit Kenneth R. Poeppelmeier 《Journal of Alloys and Compounds》2011,509(7):3310-3313
The copper borate Li2Pb2CuB4O10 has been synthesized in air by the standard solid-state reaction at temperature in the range 550-650 °C and the structure of Li2Pb2CuB4O10 was determined by single-crystal X-ray diffraction. Li2Pb2CuB4O10 crystallizes in the monoclinic space group C2/c (no. 15) with a = 16.8419(12), b = 4.7895(4), c = 13.8976(10) Å, and β = 125.3620(10)°, V = 914.22(12) Å3, and Z = 4, as determined by single-crystal X-ray diffraction. The Li2Pb2CuB4O10 structure exhibits isolated units of stoichiometry [CuB4O10]6− that are built from CuO4 distorted square planes and triangular BO3 groups. The IR spectroscopy and thermal analysis investigations of Li2Pb2CuB4O10 are also presented. 相似文献
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9.
Yuandong WuWolfgang Bensch 《Journal of Alloys and Compounds》2012,511(1):35-40
Two compounds NaCdPnS3 (Pn = As (1), Sb (2)) were synthesized as transparent yellow and red platelets by reacting cadmium powder with the molten mixtures of Na2S/As2S3/S and Na2S/Sb/S at 500 °C. Both compounds are plagued with crystal twinning and acceptable crystal structure refinement could only be obtained by identifying the type of the twinning laws. NaCdAsS3 (1) crystallizes in the monoclinic space group P21/n (no. 14) with a = 5.6561(8), b = 16.5487(15), c = 5.6954(8) Å, β = 90.315(11)°, and Z = 4. NaCdSbS3 (2) crystallizes in the monoclinic space group C2/c (no. 15) with a = 8.1329(6), b = 8.1296(4), c = 17.2600(13) Å, β = 103.499(6)°, and Z = 8. The structures of both compounds feature a 2∞[CdPnS3]− layer composed of [CdS4] tetrahedra and [AsS3] or [SbS3] pyramidal units. Between the 2∞[CdPnS3]− (Pn = As, Sb) layers the Na+ cations reside in a distorted octahedral environment of S atoms. Compound 1 is characterized with UV/Vis diffuse reflectance spectroscopy and IR and Raman spectra. 相似文献
10.
0.99(Bi0.5Na0.5TiO3)-0.01(SrNb2O6) was prepared by simple solid state reaction route. Material stabilized in rhombohedral perovskite phase with lattice constants a = 3.9060 Å, α = 89.86° and ah = 5.4852 Å, ch = 6.7335 Å for hexagonal unit cells. Density of material was found 5.52 gm/cm3 (92.9% of theoretical one) in the sample sintered at 950 °C. The temperature dependent dielectric constant exhibits a broad peak at 538 K (?m = 2270) at 1 kHz that shows frequency dependent shifts toward higher temperature - typical relaxor behavior. Modified Curie-Weiss law was used to fit the dielectric data that exhibits almost complete diffuse phase transition characteristics. The dielectric relaxation obeys the Vogel-Fulcher relationship with the freezing temperature 412.4 K. Significant dielectric dispersion is observed in low frequency regime in both components of dielectric response and a small dielectric relaxation peak is observed. Cole-Cole plots indicate polydispersive nature of the dielectric relaxation; the relaxation distribution increases with increase in temperature. 相似文献
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Min YangKuo Li Jie SuQ. Huang Wei BaoLiping You Zhaofei LiYingxia Wang Yu JiangFuhui Liao Jianhua Lin 《Journal of Alloys and Compounds》2011,509(14):4707-4713
Yb26B12O57, a rare earth oxyborate previously assigned as Yb3BO6, has been studied by various techniques including neutron and X-ray diffraction, 11B NMR spectroscopy, electron diffraction and high angle angular dark field-scanning transmission electron microscopy (HADDF-STEM). It crystallizes in the space group C2/m with cell parameters of a = 24.5780(4) Å, b = 3.58372(5) Å, c = 14.3128(3) Å and β = 115.079(1)°. The structure consists of slabs of rare earth sesquioxide and borate groups. The sesquioxide part is identified from the structural refinement, and is observed from HADDF-STEM image, while elucidation of borate groups is not straightforward. An additional oxygen atom (O31), which links two B2O5 groups into a B4O11 polyanion, is identified from the analysis of neutron diffraction data. The occupancy of this oxygen site is only quarter, which results in a random distribution of B4O11 and B2O5 groups along the b-direction. The chemical formula of ytterbium oxyborate is Yb26(BO3)4(B2O5)2(B4O11)O24, instead of the simple stoichiometric formula Yb3BO6. This compound is paramagnetic but its susceptibility deviated from the Curie-Weiss law at low temperature. 相似文献
13.
After InTeO3F and InTe2O5F recently described, a new compound In3TeO3F7 is characterized in the In-TeIV-O-F system. The crystal structure was determined by single X-ray diffraction and refined to R1 = 0.028. In3TeO3F7 crystallizes in orthorhombic space group Cmmm, a = 7.850(2) Å, b = 27.637(6) Å, c = 4.098(1) Å, V = 889.1(4) Å3 and Z = 4. Its structure consists of the stacking, via vertices, of identical layers composed of InF6 and InO2F4 octahedra sharing corners and of InO4F3 pentagonal bipyramids sharing edges and vertices. The Te cations statistically occupy one or the other of two close sites located inside tunnels delimited by the In polyhedra and are bonded to F anions located in the same tunnels.The structure can be considered as an intergrowth of parallel strips of MIn3F10 and hexagonal tungsten bronze (c)-types. It is compared to other structures such as the bronze Sb0.157WO3, TeMo5O16 and Sb2Mo10O31, phases also comprising Te4+ or Sb3+ inside hexagonal tunnels. The electronic lone pair of Te4+ is stereochemically active and a perfect O/F ordering occurs on the anionic sites. 相似文献
14.
Min Zhang Shilie Pan Jian HanYun Yang Liang Cui Zhongxiang Zhou 《Journal of Alloys and Compounds》2011,509(23):6696-6699
A novel dibarium cadmium diborate, Ba2Cd(BO3)2, has been successfully synthesized by standard solid-state reaction. Large sheet-like crystal with size up to 20 mm × 15 mm × 0.7 mm has been obtained using top-seed solution growth method. Ba2Cd(BO3)2 crystallizes in the monoclinic space group C2/m with a = 9.6305(4) Å, b = 5.3626(3) Å, c = 6.5236(2) Å, β = 118.079(3)°, Z = 2. The crystal structure is composed of isolated [BO3] triangles, [CdO6] octahedra and [BaO9] polyhedra. CdO6 are vertex-connected with six BO3 to form infinite ∞[Cd(BO3)2] layers extending in (0 0 1) plane, and two rows of Ba atoms closely occupy two side of ∞[Cd(BO3)2] layers to forming stoichiometric sheets. IR and transmittance spectrum of Ba2Cd(BO3)2 were reported. 相似文献
15.
Thin film combinatorial sputter deposited Cu6Sn5 + C alloys were prepared and found to be amorphous and/or nanostructured upon removal from the sample preparation chamber. Samples having approximate compositions (Cu6Sn5)1−xCx with 0.16 < x < 0.26 have been stored at room temperature and investigated over the course of about one year using X-ray diffraction (XRD). Simple models were employed to analyze the observed changes in the XRD patterns. Relatively sharp (nanocrystalline) components having Bragg angles corresponding to hexagonal Cu6Sn5 grew in intensity at the expense of broader (amorphous) components as a function of time. The grain size of the nanocrystalline components was approximately time independent, but depended on the amount of carbon present. The logarithm of the recrystallization time and the activation energy for crystallization appeared to be linearly dependent on the carbon content for the composition range that has been studied, as inferred from the Avrami-Johnson-Mehl equation. XRD patterns of samples with x > 0.26 appear to be relatively unchanged after a period of storage at room temperature for one year. 相似文献
16.
G.V. Bazuev A.P. TyutyunnikI.F. Berger I.V. NikolaenkoB.G. Golovkin 《Journal of Alloys and Compounds》2011,509(21):6158-6162
The complex oxide Sr4LiMn2O9 belonging to the A3n+3mA′nMn3m+nO9m+6n family (m = 3, n = 1) was prepared from a mixture of SrCO3 and LiMn2O4 in a microwave furnace by the solid state reaction. The results of structural refinements and magnetic properties are presented. The crystal structure of Sr4LiMn2O9 was solved using simultaneously X-ray and neutron diffraction data with the GSAS program in the space group P321 with unit cell parameters: a = 9.5721(7) Å, c = 7.8264(5) Å, V = 621.025 Å3, Z = 3. Sr4LiMn2O9 was found to contain 2 independent 1D chains of face-shared polyhedrons with a sequence of two octahedrons and one trigonal prism. The chains are separated by strontium cations. The refinement results show that the octahedrons and trigonal prisms in the first chain orderly contain Mn and Li, respectively, whereas the second chain is characterized by mixed occupation of these structural positions. The temperature dependence of the magnetic susceptibility of Sr4LiMn2O9 was found to be due to antiferromagnetically coupled dimers from magnetic Mn cations. 相似文献
17.
Fei ZhouLang Wu Naiming LiuYuancheng Teng Yuxiang LiJianwu Wen Xuetan Ren 《Journal of Alloys and Compounds》2012,512(1):52-56
Lead-free piezoelectric ceramics (0.8 − x)BaTiO3-0.2Bi0.5Na0.5TiO3-xBaZrO3 (BT-BNT-xBZ, 0 ≤ x ≤ 0.08) doped with 0.3 wt% Li2CO3 were prepared by conventional solid-state reaction method. With the Li2CO3 doping, all the ceramics can be well sintered at 1170-1210 °C. The phase structure, dielectric, ferroelectric and piezoelectric properties of the ceramics were investigated. Results show that a morphotropic phase boundary (MPB) between tetragonal and pseudocubic phases exists at x = 0.03-0.04. The addition of Zr can improve the piezoelectric properties of BT-BNT ceramics. Furthermore, a relaxor behavior is induced and the tetragonal-cubic phase transition shifts towards lower temperatures after the addition of Zr. The ceramics with x = 0.03 possess the optimum electrical properties: d33 = 72 pC/N, kp = 15.4%, ?r = 661, Pr = 18.5 μC/cm2, Ec = 34.1 kV/cm, Tc = 150 °C. 相似文献
18.
Lang Wu Dingquan XiaoFei Zhou Yuancheng TengYuxiang Li 《Journal of Alloys and Compounds》2011,509(2):466-470
Lead-free (1 − x − y)Bi0.5Na0.5TiO3-xBaTiO3-yBi0.5Ag0.5TiO3 (BNT-BT-BAT-x/y, x = 0-0.10, y = 0-0.075) piezoelectric ceramics were synthesized by conventional oxide-mixed method. The microstructure, ferroelectric, and piezoelectric properties of the ceramics were investigated. Results show that a morphotropic phase boundary (MPB) between rhombohedral and tetragonal phases of BNT-BT-BAT-x/0.04 ceramics is formed at x = 0.06-0.08. The addition of BAT has no obvious change on the crystal structure of BNT-BT ceramics while it causes the grain size of the ceramics to become more homogenous. Near the MPB, the ceramics with x = 0.06 and y = 0.05-0.06 possess optimum electrical properties: Pr ∼ 42.5 μC/cm2, Ec ∼ 32.0 kV/cm, d33 ∼ 172 pC/N, kp ∼ 32.6%, and kt ∼ 52.6%. The temperature dependences of kp and polarization versus electric hysteresis loops reveal that the depolarization temperature (Td) of BNT-BT-BAT-0.06/y ceramics decreases with increasing y. In addition, the polar and non-polar phases may coexist in the BNT-BT-BAT-x/y ceramics above Td. 相似文献
19.
Bryan A. KuropatwaAbdeljalil Assoud Holger Kleinke 《Journal of Alloys and Compounds》2011,509(24):6768-6772
Crystal structures and physical property measurements were determined for Tl10−xSnxTe6 with a phase range of 0 ≤ x ≤ 2.2. These tellurides are substitution variants of Tl5Te3. Electronic structure calculations indicate that Tl8Sn2Te6 should be an intrinsic semiconductor, and the Sn-poor variants, extrinsic ones with p-type conduction. The positive Seebeck values increase with increasing Sn content, while the electrical and thermal conductivity values decrease. Low thermal conductivity values, well below 1 W m−1 K−1, are the best asset of these materials with respect to thermoelectric performance. At x = 2.2, the best thermoelectric properties were obtained, with a figure-of-merit ZT = 0.60 at 617 K as determined on sintered cold-pressed pellets. 相似文献
20.
Moti Ram 《Journal of Alloys and Compounds》2011,509(18):5688-5691
In the present work, an evaluation of the structural and electrical properties of a compound (LiZnVO4) has been undertaken. This compound was prepared by solution-based chemical route. The electrical properties were measured using a.c. impedance spectroscopy method in the frequency range of 103-106 Hz at various temperatures from 28 to 300 °C. X-ray diffraction study indicates a rhombohedral unit cell structure with lattice parameters a = 14.1934 Å, b = 14.1934 Å, c = 9.4926 Å, V = 1656.12 (Å)3, α = 90°, β = 90° and γ = 120°. A field emission scanning electron micrograph reveals a polycrystalline texture of the compound with grains of unequal sizes ∼0.2-2.0 μm. The electrical conduction in the material is a thermally activated process due to the bulk effect. Frequency dependence of a.c. conductivity obeys Jonscher's universal law (σac = σdc + Aωn). 相似文献